1. Field of the Invention
This invention relates to hydrophilic siloxane copolymers and to a process for preparing them.
2. Description of the Related Art
U.S. Pat. No. 5,001,210 describes a method of producing polyurethanes wherein telechelic amino-functional siloxanes, after reaction with cyclic carbonates, are converted with di- or polyisocyanates into the target products. Polyethers are used in the form of diamino polyethers, which are costly compared with polyether diols and monools.
EP-A 1 178 069 describes the preparation of polyether urethane intermediates by reaction of alkenyl polyethers with diisocyanates and addition thereonto of silanes bearing hydrolysis-sensitive groups. Siloxane chain polymers are not obtainable in this way.
Branched polyether siloxanes are known from Chemical Abstracts 136: 38808. Hydrogensiloxanes are simultaneously reacted with divinylsiloxanes and allyl polyethers. Excess polyether remains unreacted in the product mixture. The products are used as textile softeners and are free of urethane and urea groups.
US 2003/0032726 and its equivalent WO 02/088209 (A. Andrew Shores) describe a reaction product of (A) polyisocyanate, (B) silicone having a dimethyl polysiloxane segment and one or more isocyanate-reactive groups, (C) reactant having one or more isocyanate-reactive groups and one or more ionizable groups, and (D) optionally an organic substance having one or more isocyanate-reactive groups but no ionizable groups, and (E) compound providing the counterion for said ionizable groups, wherein either the silicone (B) or the reactant (C), or both, have a single isocyanate-reactive group.
US 2003/0032751 (A. Andrew Shores) describes a reaction product of (A) polyisocyanate, (B) silicone having a dimethyl polysiloxane segment and one or more isocyanate-reactive groups, (C) reactant having one or more isocyanate-reactive groups and one or more ionizable groups, and (D) optionally an organic substance having one or more isocyanate-reactive groups but no ionizable groups, and (E) compound providing the counterion for said ionizable groups, wherein the average molecular weight of the reaction product is in the range from 600 to 20,000.